The present invention relates generally to stackable modular bodies for use in a flow metering device. Fluid flow through the flow metering device is modulated by an orifice formed in the modular bodies.
In a flow metering device, flow restrictions are used to create a pressure differential that can be used either directly or indirectly to measure flow rate with differential pressure measurement methods and pressure versus flow calibration curves. Orifice plates, wedge meters, and other types of differential flow measurements have been used for many years in the chemical and petrochemical process industry (and others) for typically large flow rates.
For a wide variety of industries such as semiconductor manufacturing or custody transfer of natural gas, flow measurement accuracy is extremely important. In other industries, such as petrochemical process analyzer flows or other general flow monitoring applications, the overall accuracy of a flow measurement is not as important as repeatability of those measurements over time. Stated another way, industries, such as the petrochemical industry, are typically more concerned with whether or not fluid flow occurs within a specific range. As long as the fluid flow rate does not dramatically change from day-to-day due to measurement repeatability error, then the user can assume that the fluid flow is stable or the process/system is stable. Conversely, the user can assume that measured flow fluctuation/changes are caused by an upset in the process, requiring attention.
In addition, petrochemical and related “dirty” industrial applications in which particulates are entrained in the fluid flow, continuous problems are encountered with the particulates clogging flow metering devices, especially those devices operating with small fluid flow passages. That is, clogging has been one of the shortfalls of orifice based flow rate measurement constructions operating under small flow rates, which constructions using small flow restrictions. Therefore, it is optimal to have a flow restriction construction that can meet the overall goals of simplified flow equations for ease of calibration and system repeatability, in addition to having the ability to not clog for extended periods of time.
Petrochemical process or analytical equipment is expected to have product lifecycles over 10 years, while other flow measurement in industries such as the semiconductor industry are only expected to last 1-3 years before replacement is required. Therefore, it is expected that the flow metering equipment must also be rugged and somewhat “fail-safe”.
What is needed is a reliable flow measurement device that has increased resistance to clogging.